Have to admit that just about the only 35mm negs I've enlarged to 16x20 were from really slow film (on RC from memory - 10 years on, the prints are fine). However I'd be game to give it a go with a grainier image and see, why not try? Looks like a decent shot too, and if they like it, then it doesn't matter. I'm all for pushing some boundaries if you see it that way. If thats any dose of encouragement.